Red shade brightener and cellulose brightening method



nited States Patent Ofilice me, sjfii l ii are called benzidinesulfonebrighteners. Several members 3,226,247 m of this class have foundcommercial acceptance; however, RED SHADE BRIGHTENER AND CELLULOSKJalthough satisfactory for certain purposes, they do not BRTGHTENIINGMETHOD Warren Schumann Forster, Basking Ridge, NJ., assignor to AmericanCyanamid Company, Stamford, Conn, a corporation of Maine always meet therequirements as to shade of fluorescence, particularly where a red shadeof fluorescence is desired. The present invention is based on thediscovery that the No Drawing Filed June 26 1963 g No. 290,632benzidinesulfone derivative represented by the formula 2 Claims. 117-335above is a useful brightener which shows unexpectedly a redder shade offluorescence and, at the same time, retains This invention relates to asubstituted benzidinesulfone the other desirable characteristics ofcertain brighteners of sulfonic acid useful as a brightener or opticalbleaching this class which make them of commercial interest. agent. Thiscompound is represented by the formula: This new brightener shows a muchmore desirable red S|O3H S0311 oun--o 0NH -NH0 o-cun S O: Salts of thecompound of Formula I with one or two moles shade of fluorescence thanother commercially acceptable of a base having a dissociation constant(K of l0 or brighteners of this family, while retaining other qualitiesgreater (e.g., NaOH, KOH, NH OH, dicyclohexylamine, such as bleachstability and strength of fluorescence. This diphenylguanidine, etc.)are also contemplated. is surprising since other very closely relatedcompounds Various types of compounds are used as brighteners or areseriously deficient in these respects, an example being opticalbleaching agents for textiles and paper. To be used the correspondingortho-position isomer. as an optical bleaching agent, a compound must besub- Thus, the new brightener has a much redder shade of stantive to thematerial to which it is applied (preferably, fluorescence than thecommercially available brightener to a variety of fibers, both naturaland synthetic), and of the structure:

(|)OH3 SOaH Sloan (|)CH3 0Ha0- -C ONH 'NHC o-0 CH3 stable and compatiblewith the soap and the detergent It is most surprising that the compoundof Formula I products with which it is blended and with which it is inis not deficient in strength of fluorescence, since the corcontact. Itshould be stable to the action of chlorine responding ortho-phenylisomer (III), shows only a fracbleaching agents during application, andafter; and for tion of the strength of fluorescence.

SOaH SIOaH (III) special purposes (such as blending with solid bleachingThus, the brightener of this invention has a desirable agents), itshould be stable when in contact with such red shade, and, in addition,it is of the order of six or more agents in the solid form even forprolonged periods. Also, times as strong in fluorescene as thecorresponding ortho the compound should have to a high degree adesirable isomer. shade of blue fluorescence when applied to the fiber.On The brightener of this invention has desirable charrepeatedapplication, the build-up effect should be a deacteristics in additionto being superior in desirable red sirable one in that the fluorescenteffect is increased, but shade of fluorescence and strength offluorescence. Thus, without producing any undesirable shade of visiblecolor it may be applied with good results to cotton and to synon thefiber. A deficiency in any one or more of these thetic fibers such asnylon and acrylic fibers. Compared properties may cause commercialrejection of the comwith the brightener of Formula II, the brightener ofthis pound. Even when a compound satisfies the requirements inventionshows 50% greater strength on nylon. It has as to substantivity,stability, chlorine fastness and strength superior build-up propertiesand excellent chlorine reof whitening effect applied to differentfibers, it is necessistance. Its chlorine resistance is of such an orderthat sary that the blue fluorescent effect have the desired shade it maybe blended with a dry bleach composition such of ol r. The l fl r n frigh ners varies fr m as calcium hypochlorite without deleteriouseffects on the a definite greenish-blue shade of fluorescent light to abrightener, definite reddish-blue shade of fluorescent light. I may beapplied to f b i by conventional Processes Under certain conditions, toachieve a desirable and 11-k i th attractive result, a brightenershowing a red shade of blue Th brightener of this invention may easily bprefluorescence may be required- For Such requirements, pared byreaction of the acid chloride of 4-biphenylcargreen shade brightenersare unsatisfactory. boxylie acid with the benzidinesulfone disulfonicacid One known class of brighteners is derived from benzpyridine salt inthe presence of phosphorous oxychloride idinesulfone disulfonic acid andthe members of this class and pyridine.

3 t This invention is further illustrated by the examples The cottonsamples are then compared under ultraviolet which follow: light andnorth daylight with the standard to determine EXAMPLE 1 S|O3H slogH To amixture of 23.2 grams of benzidinesulfone disulwhich of the applicationsof the test compound gives equal tonic acid pyridine salt, 23.7 grams of4-biphenylcarfluorescence in ultraviolet light and equivalentbrightenboxylic acid and 110 grams of pyridine, is added droping efiectin north daylight. From the amount of the wise, 11 grams of phosphorousoxychloride. The mixtest brightener required to obtain equivalentstrength of ture is heated at the reflux temperature with stirring un-15 fluorescence compared with the standard, the relative til a testshows the absence of any compound having a strength of the testbrightener versus the standard is defree amine group (approximately twohours). After termined. cooling, the solid product which precipitates,is removed In the table below is shown the strength of the brightbyfiltration. It is recrystallized from the monomethyl encr of thisinvention (the compound of Example 1) ether of ethylene glycol, versusthe corresponding o-position isomer (III) as de- EXAMPLE 2 termlned bythe foregoing procedure.

Sodium salt of the product of Example 1 TABLE I A mixture of of theCompound prepared as Exhaust on Cotton from 0.5% Brightener of Thiso-Phynl described in Example 1, 2000 ml. Of water and 10 1111. OfAnionic Detergent Solutionl Invention (p Phe nyl- Isomer 5 N sodiumhydroxide is heated to boiling with stirring Apphmwn benzoylDenvatWe)(HI) and allowed to cool slowly. The product is filtered,

100% (Standard) 16% washed with 10% brine and then dried at 55 0. E3335gg ;5gg g gi-;;; 100% (Standard) EXAMPLE 3 A stock solution of theproduct of Example 1 is pre- I claim: pared by dissolving 0.5 g. of thecompound in one liter 1: A compound selected from the group consistingof of 50% aqueous ethoxyethano-l, giving a 0.05% soluan acid oftheformula:

50 E s'o H tion. 100 ml. of this solution is diluted to one liter withand a salt thereof with bases having a K of at least water. Theresulting stock solution contains 0.005% of 10*. the compound and isused in the following procedure. 2. The method of imparting a whiterappearance to A 6 P 0f the Stock Solution in a 0116 P cellulose, whichcomprises treating cellulose with an Launder-Ometer jar is diluted to100 ml. with 44 ml. of 45 aqueous l ti f a compound of l i 1 water andml. of a 1% anionic detergent solution,

giving a solution which contains 0.06% brightener based References Citedby the Examiner on the weight of detergent. A 5 g. piece of cotton isintroduced and the Launder-Ometer is run for 25 minutes UNITED STATESPATENTS at 130 F. The cotton is removed, rinsed in water at 50 2,563,4938/1951 Scalera et 26O329-3 F. and dried at room temperature. This sampleis 2,702,759 2/1955 Scalera 6t 260329-3 used as standard. I I

A number of similar brightener applications are made WALTER MODANCEPrlmary Examiner on cotton using varying amounts of the stock solution.NICHOLAS S. RIZZO, Examiner.

2. THE METHOD OF IMPARTING A WHITER APPEARANCE TO CELLULOSE, WHICHCOMPRISES TREATING CELLULOSE WITH AN AQUEOUS SOLUTION OF A COMPOUND OFCLAIM 1.